Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is a significant public health problem in the U.S., accounting for 1.5 million emergency department (ED) visits and over 700,000 hospitalizations each year. Clinical practice guidelines for the treatment of AECOPD have been developed based on randomized controlled trials;however, the real-world clinical effectiveness of these treatments is not well understood. Further, patients with AECOPD often receive multiple medications as opposed to monotherapy in clinical trials and the comparative effectiveness for different treatment combinations is not known. We will analyze recent data from two nationally representative databases, the National Hospital Ambulatory Medical Care Survey (NHMACS) and the Healthcare Cost and Utilization Project - Nationwide Emergency Department Sample (HCUP-NEDS), to address the effectiveness/comparative effectiveness of AECOPD treatments in the ED. The specific aims of this application are: (1) to study the relationship between AECOPD quality-of-care measures and patient outcomes in the NHAMCS from 2005 to 2008;(2) to compare the outcomes in patients receiving all guideline-recommended treatments (i.e., ABCV, antibiotics, bronchodilators, corticosteroids and non-invasive ventilation) as indicated with those not receiving all guideline-recommended treatments as indicated in the NHAMCS from 2005 to 2008;and (3) to examine the relationship between AECOPD case volume and patient outcomes using data from both 2005-2008 NHAMCS and 2006-2008 HCUP-NEDS. The subaim is to identify characteristics of high-performing EDs. Guideline-concordant process measures will include inhaled bronchodilators, systemic corticosteroids, antibiotics, and non-invasive ventilation. Patient outcomes will include inpatient mortality, early inpatient mortality (within the first 3 days of admission), and length of hospital stay. Except for the analysis for the second aim, all the analyses will be performed at the ED level with the use of ED weights provided by the NHAMCS and HCUP-NEDS. The proposed study is cost-effective as it uses the existing federal data sets. The study results will have broad generalizibility by representing >100 million ED visits per year and >3500 EDs across the country. Another advantage is that the principle investigator is a well-trained physician- researcher and has a track record of publications in AECOPD and health services research. Most importantly, the study centers on effectiveness and comparative effectiveness research (CER) in a previously unstudied ED population, thereby addressing the AHRQ's mission of filling important knowledge gaps in CER. PUBLIC HEALTH RELEVANCE: Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is a significant public health problem in the U.S., accounting for 1.5 million emergency department (ED) visits and over 700,000 hospitalizations each year. Clinical practice guidelines for the treatment of AECOPD have been developed based on randomized controlled trials;however, the real-world clinical effectiveness of these treatments is not well understood. We will analyze recent data from two nationally representative databases, the National Hospital Ambulatory Medical Care Survey and the Healthcare Cost and Utilization Project - Nationwide Emergency Department Sample, to address the effectiveness/comparative effectiveness of AECOPD treatments and to identify characteristics of high-performing EDs.